This invention relates to thickener compositions which show synergistic thickening effects. The compositions are mixtures of a polymer of 2-acrylamido-2-methylpropane sulfonic acid and certain water soluble polymers such as the galactomannan gums, derivatives thereof, cellulose derivatives and polyalkylene oxide polymers.
Various polymers have been used in the past to thicken liquids such as water, alcohols and mixtures thereof. Problems sometimes occur such as insufficient viscosity levels, rapid viscosity degradation, insolubility or precipitation of the polymer hydrolysis products through insolubilization by multivalent ion salts. The homopolymers of 2-acrylamido-2-methylpropane sulfonic acid have more recently come of interest but thickened solutions possessing greater viscosities and/or suspending power are desired. Illustrative patents relating to the use of such polymers are U.S. Pat. Nos. 3,931,089, 4,065,422, 4,128,631, 4,332,688 and 4,242,098. The galactomannan gums such as guar and locust bean have been long recognized as producing high viscosity sols. Processes of producing such gums from their beans can be seen from U.S. Pat. Nos. 2,891,050, 3,455,899, 353,823 and 3,132,681. Derivatives of such gums such as hydroxyalkyl ethers have found particular utility in formation fracturing applications such as seen in U.S Pat. No. 3,483,121. Other known thickeners are the polyalkylene oxide polymers, such as those of polyethylene oxide, and the alkyl ethers of cellulose.